As shown in FIG. 13, an image display apparatus, which emits invisible light L1 from a light emitting device 11 to a pointing device 10 for detecting a position of the pointing device 10 which is used to point out an optional position on an image G1, is conventionally known (see Japanese Laid-Open Patent Publication No. 2006-277357, for example). In such image display apparatus, a retroreflector member, which deflects the invisible light L1 from the light emitting device 11 and reflects the invisible light L1 to the incident direction, is provided on the pointing device 10. The invisible light L1 which is reflected by the pointing device 10 is received by a photoreception means in the light emitting means 11. The position of the pointing device 10 is estimated based on a photoreception timing of the invisible light by the photoreception device.
By the way, it is difficult to substitute the pointing device 10 with a finger or fingers of a person in the conventional technology, so that it is difficult to reduce a number of components. In addition, the conventional apparatus requires a high time-resolution in order of pico-second (ps) for positional detection based on the photoreception timing of the reflected light, and thus, it needs a complicated and high-performance detect circuit. Thereby, manufacturing cost rises.